Rotary internal-combustion engine



Jan. 23, 1945. J E, @mn-,TH 2,367,676

ROTARY INTERNAL-COMBUSTION ENGINE Filed July 27, 1943 6 Sheets-Sheet 1FIG. 3

INVENTOR. JAMES E-.GRIFFITH A TTURNEY.

JM 23, 1945' 6 J." E. GRIFFITH 2,367,676

ROTARY INTERNAL-COMBUSTION ENGINE Filed July 27, 1943 6 Sheets-Sheet 275 Ca f C Cd. Pa,

1 o 36 a* P 4/ 35 FIG. 7

INI/ENTOR;v JAMES E.' Gm FFI'TH ATTORNEY.

Jane 23, 1945.

.L E. GRIFFITH ROTARY. INTERNAL-COMBUSTION ENGINE Filed July 27; 1943 6Sheets-Sheet 3 H .W ma. N Vr WR WG. E S .E M A J A TTORNE Y.

Jan- 23 l945- .l GRIFFITH 2,367,676

ROTARY INTERNAL-COMBUSTION ENGINE y Filed July .27, 1943 6 Sheets-Sheet4 P8 INVENTOR.

. JAMES EGM-'HTH A TTURNE Y.

Jan. 23, 1945. L E GRlFFlTH 2,367,676

ROTARY INTERNAL- COMBUSTION ENGINE Filed July 27, 1943 V 6 Sheets-Sheet5 BYWMW A TTORNE Y.

Jan. 23, 1945. j 1. E. GRIFFITH 2,367,676

. ROTARY INTERNAL-COMBUSTION ENGINE n Filed July 27, 1945. esheets-sheet esl INVENTOR.

JA M55 E H/FF/ TH' BY E FIG. 24 F1625 WM @4M A TTORNEY.

Patentecl Jan., 23, 1945 UNITED STATES PATENT OFFICE-f ROTARYINTERNAL-COMBUSTION ENGINE James E. Grith, Denver, Colo.

Application July 27, 1943, Serial No. 496,361

(Cl. 12S-11) 11 Claims.

This invention relates to improvements in rotary internal combustionengines of the type described and claimed in Patent No. 2,304,406,granted to me on December 8, 1942.

For many purposes the ordinary reciprocating internal combustion engineis Well suited, but for other purposes an engine of the rotaryv typewould be more desirable.

It is the object of this invention to produce a rotary internalcombustion engine of the general type referred to and which shall havethe characteristics of a two-stroke cycle engine. A

The principal object of the invention is to produce an engine of greatereiciency and of simpler construction than similar engines and which isof such design that it can be manufactured without the necessity of a,large amount of special machinery.

Another object is to produce an engine in which each unit isindependent, but of such construction that as many units as may bedesired can be arranged to cooperate so as to form a multi-unit engineof any desired horse power.

'In order to describe the invention in such a manner that it can bereadily understood, reference will now be had to the accompanyingdrawings in which the invention has been illustrated in its preferredform, and in which:

Figure 1 is a vertical section taken on lines l-I, Figures 2 and 3;

Figure 2 is an end View looking in the direction of arrow 2, in Figure1;

Figure 3 is an end view looking in the direction of arrow 3, Figure l;

Figure 4 is a vertically oblique view of the movable parts comprisingthecompression and power pistons with associated sealing-members;

Figure 5 is a side elevation of one piston assembly;

Figure 6 is a view similar to that shown in Figure 5 and shows anotherpiston assembly;

Figure 7 is a transverse section taken on line l-l, Figure 5;

Figure 8 is a transverse section taken on line 3 8, Figure 6;

Figure 9 is a section taken on line 9 9, Figure 1;

Figure 10 is a section taken on line IIJ-I0,

Figure 12;

Figure 11 is a section take on line Il--I l, Figure 12;

Figure 12 is a section taken on line |2-I2, Figure 10;

Figure 13 is a section taken on line I3-I3,

Figure 12;

Figure 14 is a plane View showing a segment of the cam ring;

Figure 15 is an elevation looking in the direction of arrow l5, Figure14;

Figure 16 is a detail view showing, to a somewhat enlarged scale, theinterlock between the piston and the cylinder head, taken along line16v-I6, Figure 13;

Figure 17 constitutes a group of sections taken in pairs along thetransverse lines I'l-|'|, Figure 1 and shows the progressive positionsof the compression and power pistons, together with the rotary valvesleeve' which contains the ex haust and intake ports; f

Figure l8-is a vertical longitudinal section of a, modified constructiontaken on line Iii-i8, Figure 19;

Figure 19 is an end elevation taken on plane l9-l9, in Figure 18;

Figure 20 is a section taken on line 20-20, Figure 18; A

Figure 21 is a section on line l2 I-2l, Figure 18;

Figure 22 is a side elevation of a piston assembly and corresponds toFigure 5;

Figure 23 is an end elevation looking in the direction of arrow 23 inFigure 22 and corresponds to Figure 7 Figure 24 is a side elevation ofthe other assembly and corresponds to Figure 6;

Figure 25 is an end elevation looking in the piston l direction of'arrow25 in Figure 24;

Figure 26 is adetailed view showing a portion of the apparatus and istaken along line 2|-2l,

in Figure 18; and

p Figure 27 is an enlarged detailed view showing the parts illustratedin Figure 18 to a somewhat larger scale.

In the drawings reference numeral 20 designates the engine cylinder andreference numerals 2| and 22 designate the cylinder heads. The heads aresecured to the ends of the cylinder by suitable means such as the welds23 shown in Figure 1. Reference numeral 24 designates a rotary valvethat is divided into two compartments by means of a transversediaphragm`25. The ends are closed by covers 26 and 21 which have beenshown as integral with the valve cylinder, but which may be formed fromseparate parts and removably secured thereto. At each end of thecylindrical valve are tubular projections 28 and 29, the former beingconnected with a carburetor and the latter to an exhaust pipe. Thecarburetor and the exhaust drlcal wall of valve 24 is provided with anintake port 30 and an exhaust port 3|. These ports are positioned onopposite sides of the center diaphragm and are angularly displaced to anextent and -for a purpose which will be hereinafter explained.

Positioned within the cylinder and between the cylinder heads are twopiston units which have been shown separately in Figures and 6 and inassembled relation in Figure 4. The unit shown in Figure 5 consists of aring 32 terminating in a gear 33. Formed integral with the inner end ofring 32 is a piston Ca and secured to the other end of this piston is aring 34 having two annular areas of different thickness forming a rabbet35. Extending outwardly from the center opening of this ring is a shortcylindrical member or ring 36 and secured to the end of this ring is apiston Pa. The other piston assembly which has been shown in Figure 6,comprises a short cylindrical ring 31 from the outer end of which a gear38 projects. Formed integral with the inner end of the cylindrical ring31 is a piston P. Secured to the inner end of this piston is a ring 39that is provided on its inner surface with a. rabbet 40 of the same sizeand dimension as that designated by 35 in Figure 5. A short ring 4l isintegrally connected with piston P and secured to the inner end of thisring is a piston C. It will be observed from Figure 8 that there is anannular gap 42 between the inner edge of ring 39 and the outer surfaceof ring 4I. The thickness and diameter of this annular gap or opening issuch that it will receive, with a sliding t, the ring 36 carried by thepiston assembly shown in Figure 5. It may be explained at this pointthat piston C is formed in two parts, the part designated by referencenumeral 43 being integral with ring 4I and to this projecting portion 43a piston C is secured by screws or other suitable means which have notbeen shown. Assuming now that piston C is removed from the part 43, thetwo piston assemblies can be interconnected by inserting the one shownin Figure 6 into the one shown in Figure 5 and after the parts have beenthus assembled, piston C is secured to the part 43, whereupon the twopiston units will form an assembly like that shown in Figure 4.Referring now to Figures 7 and 8 it will be seen that ring 34 isprovided with two ports, 44 and 45, one located at each side of pistonCa and from Figure 8 it will be seen that ring 39 is provided with twosimilar ports designated by 44a and 445a, one on each side of piston P.The two piston units assembled as above are positioned on the rotaryvalve 24. The piston assembly is now inserted into the cylinder 20,which is made in two sections which are secured together by means ofbolts 46 that'pass through the flanges 41. Before the two piston unitsare assembled, the cam ring 48 is positioned between the two rings 34and 39 in the annular recess formed by the complementary rabbets 35 and40. The cam ring 48 is provided with a groove 49 that extends through anangular distance of about 315 degrees beginning at the vertical shouldermarked `50 and terminating at the incline 5I. There is a similar grooveon both sides of the ring as shown in Figure l5. Locking pins 52 and 53are positioned respectively in the pistons marked C, Ca and P, Pa in themanner shown in Figure 12. A helical compression spring 54 surroundseach pin and urges it towards the cam ring 48. Each of the locking pinshas a conical head 6B that is adapted to engagein a depression 68 on theinner surface of one of the cylinder heads. The cam ring is provided onits outer surface with gear teeth 51. Secured to the cylinder 20 is ahousing 58 having opposed bearings in which the drive shaft 59 isjournaled. The drive shaft is also journaled in bearings 60 in theextensions 6| and 62 of the cylinder head 2l and 22. An idler gear 63 ispositioned within the housing 58 and rotates in the bearings 64. A gearl 65 is positioned within the housing 58 and is in mesh with gear 63.The gear teeth of the idler 63 mesh with gear teeth 51 on ring 48. Thegear ratio between gear 65 and the cam ring 48 are as 1 to 4, that is,gear 65 will rotate four times in order to rotate the cam ring onerevolution. Relative directions of rotation are indicated by arrows inFigure 9. At the bottom of the cylinders, there is a removable housing66 in which is journaled a shaft 61. A gear 68 is secured to the innerend of shaft 61 and is in mesh with the gear on the cam ring. Shaft 61has its outer end journaled in a bearing 69 and secured to the outer endof this shaft is a gear 10. Gears 68 and 10 have the same pitchdiameter. Secured to o1' formed integral with the valve cylinder 24 is agear 1|. This has the same pitch diameter as the gear on cam ring 48. Itfollows from the above that the valve cylinder 24 rotates at the sameangular speed and in the same direction as the cam ring and it alsofollows that the valve cylinder rotates once for each four revolutionsof the drive shaft 59.

Secured to the ends of the drive shaft on the outside of the extensions6| and 62 are gear wheels 12 and 13, respectively. It will be observedfrom Figures 2 and 3 that these gears are incomplete, that is, they areprovided with gear teeth through an angle of degrees only, the remainderof the periphery being smooth as indicated by reference numerals 14.Gear wheel 12 is positioned to mesh with gear 33 and gear wheel 13 ispositioned to mesh with the gear 38. It has previously been explained inconnection with Figures 5 and 6 that gear 33 is connected with thepiston assembly comprising the compression piston Ca and the powerpiston Pa, together with the sealing rings 34 and 36. Whereas, gear 38is connected with the piston assembly comprising the power piston P andthe compression piston C, together with the sealing rings 39 and 4 I.

Reference will now be made to Figure 4, in which is shown the relativepositions of the two piston assemblies at the beginning of rst powerstroke. The two pistons C and Ca are very close together and have beenshown as separated by a narrow gap designated by numeral 15. The powerpistons P and Pa are narrower in an angular sense than the compressionpistons and are separated by a space which has been designated byreference numeral 16 and which is wider than the space 15. In thisinitial position, the ports 44 and 44a are in alignment and this porthas been designated by reference character 44a in Figure 4. With theparts in this position, I will proceed to explain the sequence ofoperation. The position shown in Figure 4 is that which corresponds tothe diagrams C1 and P1 in Figure 17. It might be explained here that thegroups of figures shown in Figure 1'1, have been arranged in pairs ofwhich C1 and P1 indicate the first position and that each of thesucceeding pairs designate the starting position at the ends of each pismovement, there being eight consecutive movements to a complete cycle,the last one being designated by Ca and Ps.

With the parts positioned as shown in the rst group in Figure 17, let usassume that the drive shaft is turned manually by means of a crank 11 inthe direction of the arrow in Figure 1. This rotation will produce anengagement between the gear teeth on gear wheels 13 and gear 38 and as aresult gear 38 with its attached pistons Fd and Ca will be rotated in acounterclockwise direction when viewed as in Figures 4 and 17. .as soonas this relative rotation begins, the opening through the ports 44 and44a will close and when the piston Ca has moved a comparatively shortdistance, it uncovers the intake port 30, as will be seen from Figure17. Since the intake port is in communication with the carburetor anexplosive fuel mixture will be sucked into the compression chamber,which is thus being formed. When gear 13 has completed a half arevolution, the two piston assemblies will be in the position shown inCz and P2 in Figure 17. The pistons C and P will have remainedstationwhereas the pistons Ca and Pa will have through an angle of 270degrees, or LA of a complete circle. During this movement of the pistonassembly, the space between the two pis- C and Ca will become lled withan explosive mixture which will occupy all of the space designated byreference numeral 18 in C2 of Figil. Upon further rotation of shaft 59,gear eels 12 will move into operative engagement 'i the gear 35i on thepiston assembly shown gure and when shaft 59 has completed its irevolution, the pistons will be in the position wn in C3 and F3 ofFigure 17. The chamber I ci C2 has now been reduced in size as indicateda in C3. Whereas another chamber 18 is d with an explosive gas mixture.It will be `ved from P3 in Figure 1'7, that the two piss Po: and P arepositioned adjacent each other shown and that they are in communicationi the compression chamber 18a through the rts lil and il-fla. A sparkplug 19 is carried by rotary valve 24 and at the end of each stroke eelectrodes are in communication with the chamber d. The engine is nowprimed d when the charge in chamber 80 is ignited, it will expand in theusual manner and increase the pressure. rIhis will cause the piston Pawith attached piston Ca to be rotated by the ex-, sive force of theexploding gas and since at is point gear 13 is in position to be engagedgear wheel 13 with its attached parts, iely. gears t5 and gear wheel 12will be rod in the direction of the arrows in Figures 2 tion shown inFigure 4, that point of gear heel which is at the top in Figure 3 willbe the bottom and in position to be engaged by gear wheel 33. At thispoint the chamber 8| on the following side of the piston Pa will haveuncovered the exhaust port 3l.A Chamber 8l is now full of exhaust gases,which, at this point, e cape through the exhaust port. When the "gechamber 39 is ignited, piston assembly 'ising pistons C and P. will thenstart r0- g until the parts reach the position shown in t P5 and this iscontinued in a progressive manner until the parts again arrive in theposii' 'as shown .in C1 and P1 having thus completed li have beenillustrated in Figure 17.

ld o. When pistons Ca and Pa arrive at the It will now be explained howthe pistons are locked and released so as to form stationary abutmentsand power pistons alternately as the engine operates. It has alreadybeen explained how the rotation of shaft 59 is communicated by means ofgears 65 and 6-3 tothe cam ring 48 and how the motion 'of the latter istransmitted by means of shaft 61 and gears 68 and 10 and 1| to therotary valve 24. The gear ratios, as have already been explained, aresuch that for each half rotation of shaft 59, the rotary valve 24 willturn through an angle of 45 degrees and since this valve and the camring turn at the same angular speed, the latter will also move throughan angle of 45 degrees for each half revolution of shaft 59.

It will be observed from the drawings that the rotary valve 24 and thecam ring turn in a clockwise direction, when viewed as in Figure 9,whereas the pistons move in a counterclockwise direction. It thereforefollows that when the pistons have moved of a revolution and the camring and the valve 24 have moved in the opposite direction 1/8 of arevolution, the parts will arrive in the same relative position as theywere for the beginning of the next stroke. "Ihe pistons will make eightsuccessive rotations for each complete cycle and the positions for eachof these rotations are shown diagrammatically in Figure 17.

It will now be explained in what manner the pistons that have beenoperative to produce power will become latched against return movementat the end of etach rotation so as to form abutments for the powercylinders during the firing or power rotation, and for the compressionand intake cylinders.

Attention has already been called to the cam ring 48 and to theoppositely positioned cam grooves 49; from Figure l2 it will be seenthat the two pistons of each assembly are provided with a locking pin 52having one end provided with a conical head and the other positioned inthe cam groove 49. When the ends of the locking bars are in the camgrooves 49, the pistons are free to rotate in the cylinder because thespring 54 will then function to remove the head 55 from the depression56 in the cylinder heads. When the locking pins arrive at the inoline5I, they are moved outwardly and into engagement with the depressions 56The lockiing pins are constructed of two parts as shown in Figure 16 andthese are urged apart by meansof a spring 82 which is compressed as theinclines 5| move the locking pins outwardly. At the point where one setof locking pins are moved into operating engagement, the other vsetdrops oir into the groove 49 at theshoulder 50, thus releasing the frontpair of pistons at the time that the rear pair is locked. Since the ring48 moves 1/8 of a revolution in the time that the' pistons move 3A of arevolution, the locking pins will be operated at the same relativepoints during each stroke and there will therefore be a continuoussuccession of piston strokes during each of which one charge of gas isiired yand the gases of combustion from the prior power strokeexhausted, a new cliarge'sucked into the engine and another chargecompressed ready to be transferred to the ring cylinder alternatelythrough the opening produced by the registration of ports 44, 44a and45, 45a.

In the drawings the specic means for sealing the several relativelymovable parts has not been shown because it is contemplated that meansalready used in similar engines to effect a similar sealing operationwill be employed. The means employed for effecting a seal between thepistons and the cylinder walls may be an adaptation of the means shownin United States Patent No. 1,305,966, patented June 3, 1919. For otherparts of the engine suitable sealing means are to be employed, but sincethe invention is not limited to this particular feature, they have notbeen shown for to do so would merely complicate the drawings.

In the embodiment illustrated in Figures 1 to 16, inclusive, motion istransmitted from the piston units to the drive shaft by means of certaingears including the interrupted gears 'l2 and 13. In Figures 18 to 27,inclusive, a modification has been shown in which the power from thepistons is transmitted to the drive shaft by means which do not requirethe gears 12, 13, 33 and 38 and which therefore materially alters theappearance of the engine while maintaining the principle of operationand the important mechanical elements which have already been described.

Since this modification contains many elements that are identical andsome which are merely slight variations of those shown in the embodimentabove explained, such similar e1ements have been designated by the sameor similar reference characters.

The cylinder 20a is constructed as a single unit and is provided withoutwardly extending anges 41a at each end. The cylinder heads have beendesignated by reference numerals 2Ia and 22a. Secured to each cylinderhead is a plate 83 having a bearing 84 in which the shaft 53a rotates.The cylinder and cylinder heads are supported on some suitable base likethat designated by reference numeral 85 which is merely illustrative ofa base and the specific construction has therefore been shown in adiagrammatic manner.

In this embodiment the cylinder', which was shown in two parts in thefirst modification, has been shown as made of one single part and therotary valve 24a, which corresponds to 24 in Figure 12, is made in twoparts. The interior surface of each part 24a is provided with internalgear teeth 86 that are engaged by the teeth of an idler 81 which ismounted for rotation on a shaft 88 that turns in or is carried by thebear ing 89, The shaft 59a is provided with gear teeth 98 that engagethe idler. Since the tubular valve 24a is made in two parts, there aretwo setsof gears like those indicated in Figures 18 and 19. The gearratio between the rotary valve and the shaft is as l is to 6 whichcorresponds to the l to 4 gear ratio between valve member 24 and shaft59 in the first embodiment. It will be observed that the shaft 59a andthe tubular valve 24a rotate in opposite directions. In thismodifcation, it will be assumed that shaft 59a turns in acounterclockwise direction when viewed as in Figure 19 and consequentlythe valve 24a turns in a clockwise direction. Secured to the shaft is adisk 9| that terminates in a cylindrical flange 92. This flange extendsto both sides of the disk as shown most clearly in Figure 27. The twoValve portions 24a are provided with radially extending flanges 48awhose peripheries extend to the inner surfaces of the flanges 92 asshown in Figure 27.

Referring now to Figure 26 it will be seen that the flanges 48a areprovided on their outer peripheries with rabbets 49a which correspond tothe grooves 49 shown in Figures 14 and 15.

These rabbets begin at the vertical shoulder 50a and end in the inclineSla the distance between the shoulder 5| a and the incline beingsubstantially forty-five degrees, the same as in Figure 14.

The ends of flange 82 are each provided with notches 93 for thereception of the plunger 94 which corresponds to the end 53h in Figure16. Each piston is provided with a plunger 53a that is made in twoparts. The inner part has been designated by 94 and has an opening forthe reception of the end of plunger 53a. A spring 54a urges the plungerinwardly and another spring 82a urges the two parts away from eachother. It will now be apparent that when the part 94 rests on theflatsurface of flange 48a between the ends of the rabbet 49a, the end ofthe plunger 53a will be urged outwardly into the recess 56a in cylinderhead 22a. The piston assembly will therefore be latched against rotaryymovement relative to the cylinder head in the manner explained inconnection with the first embodiment. It may be explained here that theinner surfaces of the cylinder heads are provided with depressions 56like those shown in Figure 13. As will be hereinafter explained, thevalves 24a rotate in a clockwise direction when viewed as in Figures 19and 26. When the shoulder 50a passes beyond the 'plunger 94, the latterdrops into the rabbet and at that particular time the piston assembliesare so related to the rotating disk that, as the plunger drops from theflat surface, it will extend into the corresponding notch 93 andinterconnect the piston assembly with the disk 9|. The two parts willtherefore be constrained to rotate in unison until they are separated bythe action of the incline Sla. Since the power shaft is interconnectedwith the valves 24a in such a way that the latter rotates at one sixthof the angular speed of the shaft, in the opposite direction, thepistons and shaft will rotate three-fourths of a revolution during thetime that the rotary valve turns one-eighth of a revolution and theparts will therefore get into the same relative position from which theystarted, four times during each cycle of operation. (By a cycle in thisrelation is meant the number of power strokes required to bring thepiston and parts back to the position shown in Ci, P1, Figure 17.) Whena piston unit arrives at the points Where the incline 51a commences, thestationary unit thatl is held against rotation in the cylinder by meansof the plunger 53a that is held in latching position so long as the part94 rests on the fiat surface between the ends of the rabbet 49a isreleased. When the plunger of the moving unit of pistons arrives at thetop of the incline, the other plunger will drop over shoulder 50a ontothe bottom of the rabbet and into one of the latching grooves 93. Itwill be seen that when one piston unit is unlatched from the cylinderheads it will immediately become latched to the power shaft and at thesame time the piston unit that was latched to the shaft is released andbecomes latched in stationary position. This latching and releasingtakes place at the end of each power stroke and occurs eight timesduring each cycle. It might be explained here that the engine can bedesigned so that greater or lessernumber of power strokes are requiredper cycle and that eight has been selected because it gives a convenientway of illustrating and explaining the operation.

With the constructions described, only a single spark plug is requiredsince it is attached to the rotary valve member 24 and thereforemaintains a fixed position with respect to th pistons at the point wherethe charge is to be gni ed.

The timing mechanism has not been shown, but it may be explained thatcooperating contacts one on the rotary valve and a plurality on thecylinder head may be employed.

The compact arrangement of the parts in the modilication shown inFigures 18 and 25 produce an engine of neat appearance.v

The carbureter connection and the exhaust have been designated,respectively, by reference numerals 28 and 29 in Figure 18. The intakeand exhaust ports 30 and 3| have not been shown in Figures 18 and 25,but it is to be understood that they are positioned as shown iny Figurel and described in connection with Figures 1 to 17.

From the above description, when taken in connection with the drawings,it will be seen that the engine herein disclosed is of such constructionthat instead of reciprocating in the usual manner, the pistons rotate inannular cylinders and alternately form the abutments and movable powerpistons. Such engines are admirably adapted for interconnecting so as toincrease the power output to any multiple of that delivered by anysingle unit.

Since there are two power pistons P and Pa and since they functionalternately, it is evident that each piston makes four power strokes foreach cycle and that the length of the stroke is 270 degrees.

Having described the invention what is claimed as new is:

1. In an internal combustion engine of the rotary type, an annularcylinder, two piston units mounted for movement in the cylinder, eachunit comprising an assembly of two longitudinally spaced pistons, thepistons of each unit being interconneoted at their opposed adjacent endsby a ring concentric with the cylinder, the pistons of one assemblytraveling in the same path as the correspondingly positioned pistons ofthe other assembly, the piston assemblies being movable alternately andforwardly by a step by step movement, means for latching one unit ofpistons against movement relative to the cylinder atthe end of itsstroke and for simultaneously releasing the other unit, a drive shaftparallel with the axis of the cylinder, means for interconnecting thereleased piston unit with the drive shaft and for maintaining it ininterconnection until the same is latched to the cylinder head.

2. In an internal combustion engine of the rotary type, an annularcylinder, two piston units mounted for rotation in the cylinder, eachunit comprising an assembly of two longitudinally spaced pistons, thepistons of each unit being interconnected at their opposed adjacent endsby a ring concentric with the cylinder, the pistons of one assemblytraveling in the same path as the corresponding positioned pistons ofthe other assembly, the piston assemblies being movable alternately andforwardly by a step by step movement. means for latching one unit ofpistons at the end of their stroke and for simultaneously releasing theother unit, the piston units having hub portions terminating in gearspositioned outside of the cylinder, means comprising a drive shaftrotatable about an axis parallel to the axis of the cylinder and twoincomplete gears carried by the shaft for interconnecting the pistonsfor alternate forward movement, a rotary cylindrical valve positionedand journaled in the piston assemblies, and means for rotating therotary valve at a speed one-fourth that of the shaft and in a directionopposite to that at which the pistons travel.

3. An internal combustion engine comprising an annular cylinder, astationary support therefor, a head at each end, each of which has abearing concentric with the cylinder, two piston units positioned in thecylinder, each piston unit comprising a gear positioned on the outsideof a cylinder head, a pivot ring carried by the outer piston of eachunit and mounted for rotation in the cylinder head bearing, twolongitudinally spaced pistons, a sealing ring positioned at the spacebetween the pistons and interconnecting them, each piston unit having avalve ring rigidly attached to theinner end of the outer piston, arotary cylindrical valve positioned Within the piston units, said rotaryvalve having a partition dividing it into two compartments, the wall ofone compartment having an opening forming an intake port and the wall ofthe other compartment having an opening forming an exhaust port,

a power shaft mounted for rotation about an axis positioned outside ofthe cylinder, means for rotating the cylindrical valve at a speedone-fourth that of the shaft, and in the opposite direction, andinterconnecting means between the shaft and each piston assembly foralternately rotating each piston assembly seven-eighths of a revolution,in a direction opposite to that in which the cylindrical valve rotates,during each half revolution of the shaft, and ignition means for themotor.

4. An internal combustion engine, comprising in combination, astationary outer cylinder, an

annular closure for each end thereof, a cylindrical valve mounted forrotation in the openings in the end closures, bearings positionedoutside of the cylinder, a power shaft mounted for rotation in thebearings, the axis of the shaft being parallel with the axis of thecylindrical valve, two piston units mounted for rotation in the annularspace between the cylinder and the rcylindrical valve, each unitcomprising two longitudinally spaced pistons, one piston of each unitand the correspondingly positioned piston of the other unit forming apair, the two pistons of each unit being interconnected by meanscomprising a narrow cylindrical ring, the two rings being of suchdiameters that one will t ver the other, a flat ring secured to theinner end of one of the pistons of each unit, one of the rings having agas tight connection with the larger interconnecting ring, meanscomprising a gear mechanism for alternately rotating the interconnectedpistons of the two pairs through a predetermined angular distance, meansfor latching the pistons at the end of each angular movement, means fordelivering a charge of compressed gaseous fuel into the space betweenadjacent pistons of one pair at the end of the angular movement, meansfor igniting the fuel whereby the unlatched piston will be given arotary movement, and means for transmitting motion from the rotatingpiston to the drive shaft.

5. An internal combustion engine comprising a cylinder having cylinderheads provided with bearings concentric therewith, two piston unitspositioned in the cylinder, each unit comprising a cylindrical journalportion for cooperating with the bearing in one cylinder head, the outerends of the journals being formed with gear teeth, each unit comprisingtwo longitudinally spaced pistons, one of which is attached to the innerend of the cylindrical journal, a sealing ring attached to the inner endof the piston that is attached to the cylindrical journal, a sealingring interconnecting the spaced pistons which are positioned in axialalignment with each other, the inner end of the rst mentioned piston ofeach unit having secured thereto a combined partition ring and valve,each partition ring having a port opening on each side of the piston towhich it is attached, a cylindrical rotary valve positioned in thepiston assemblies, said rotary valve having its interior divided intotwo chambers by a transverse partition, the wall in one chamber havingan opening forming an intake port and the wall in the other chamberhaving an opening forming an exhaust port, means for effecting acontinuous rotation of the rotary valve, comprising, a shaft, and meansalso comprising the shaft and a gear connection for alternately turningthe piston units through angles of 315 degrees during the time that therotary valve turns through an angle of 45 degrees, and means for lockingone piston assembly and releasing, the other at the end of eachrotation.

6. An internal combustion engine having, in combination, a cylinderprovided with opposed heads having bearings concentric therewith, twopiston units mounted for rotation in the cylinder, the ends of thepiston units comprising short cylindrical sections journaled in thebearings in the cylinder heads, the outer end of each cylinder journalsection having gear teeth, each piston unit comprising twolongitudinally spaced pistons, one of which has one end connected withthe inner end of a cylindrical journal section, a ring concentric withthe journal section, connected with the inner end of the rst piston, thesecond piston being also connected with the ring,

' the inner end of the outer piston of each piston assembly havingsecured to it a ring provided with ports adjacent the opposite sides ofthe piston to which it is attached, the two rings forming a partitionseparating the cylinder into two annular chambers, one of which forms acharge forming and compressing device and the other the power producingengine, the two partition rings having complementary rabbets, an annularcam ring positioned in the recess formed by the rabbets, the peripheryof the cam ring having gear teeth, locking means in each pistoncomprising bars adapted to project through the ends thereof, one end ofeach locking bar engaging a side of the cam ring having a cam groove anda cam on each side, resilient means for urging the locking bars intoengagement with the cam ring, the inner surfaces of the cylinder headhaving angularly spaced recesses for the reception of the locking bars,a rotary cylindrical valve positioned in the piston assemblies, meanscomprising gears for effecting a simultaneous and equiangular rotationof the cam ring and the rotary valve, in the same direction, the valvebeing divided into two chambers by a transverse partition, the wall inone chamber having an opening forming an intake port, the wall in theother chamber having an opening forming an exhaust port, a drive shaft,a gear device for transmitting rotation from the shaft to the cam ringat a given ratio, and in the same direction, and means for effecting anintermittent and alternate rotation of the piston units in a directionopposite to that in which the cylindrical valve rotates.

7. An internal combustion engine of the rotary type comprising acylinder formed by a cylindrical member whose ends are provided withclosures having bearings concentric therewith,

two piston units positioned in the cylinder, each unit comprising a ringjournaled in a bearing in a cylinder head, a piston attached to theinner end of the ring, a sealing ring attached to the inner end of thepiston and a second piston attached to the inner end of the sealingring, combined sealing and valve rings attached to the inner ends of thefirst mentioned pistons, each valve ring having two port openings, oneon each side of the piston to which it is attached, a rotary valvepositioned in the valve assemblies, the interior of the rotary valvebeing divided into two chambers by a transverse partition, one chamberbeing in communication with a source of explosive fuel and the otherwith an exhaust pipe, the wall of the rotaryl valve having two angularlydisplaced ports communicating the chambers with the engine cylinder,means for alternately turning the piston units through a given angle,means for automatically latching and releasing the piston units at theend and at the beginning of each movement, and means for turning therotary valve member in the opposite direction to that at which thepistons move and through an angle equal to the difference between theangular movement of the piston and 360 degrees during each pistonmovement.

8. In an internal combustion engine of the rotary type, an annularcylinder, two piston units mounted for movement in the cylinder, eachunit comprising an assembly of two longitudinally spaced pistons, thepistons of each unit being interconnected at their opposed adjacent endsby a ring concentric with the cylinder, the inner piston of one assemblytraveling in the same path as the outer piston of the other assembly,the piston assemblies-being movable alternately and forwardly by a stepby step movement, means for latching one set of pistons against movementrelative to the cylinder at the end of its stroke and for simultaneouslyreleasing the other set, a drive shaft mounted for rotation about anaxis coincident with the cylinder, means operated by the latching andreleasing means for interconnecting the piston unit that has beenreleased from the cylinder to the drive shaft, whereby the rotarymovement of the piston will be transmitted thereto and for releasing theother piston unit from the drive shaft as soon as it is latched againstfurther rotation relative to the cylinder whereby the shaft will receivesuccessive impulses from the two piston units.`

9. A piston unit for use in a rotary internal combustion engine,comprising a cylindrical sealing ring, and two pistons carried thereby,one at each end of the ring, the pistons each having a portion extendingbeyond the outer surface of the ring, a flat ring lying in a planeperpendicular to the axis of the sealing ring, surrounding the latterand concentric therewith, carried by the inner end of one of thepistons, said flat ring having an opening on each side of the piston towhich it is attached, the two openings serving alternately as ports forthe passage of compressed gases.

10. In a rotary internal combustion engine, an annular cylinder, twopiston units mounted for movement therein, each unit comprising anassembly of two longitudinally spaced pistons, the pistons of each unitbeing interconnected at their adjacent ends by a ring concentric withthe cylinder, the corresponding pistons of the two units beingpositioned to move in the same path, the two units being movablealternately by a step by step motion, the cylinder having cylinderheads, a .power shaft rotatably connected with the cylinder, and meansfor alternately connecting and disconnecting the piston units with thecylinder heads and with the power shaft.

1l. In a rotary internal combustion engine, an annular cylinder, twopiston units mounted for movement therein, each unit comprising an as`sembly of two longitudinally spaced pistons, the pistons of each unitbeing. interconnected at their adjacent ends by a ring concentric withthe cylinder, the corresponding pistons of the two units beingpositioned to move in the same path,

the two units being movable alternately by a. step by step motion, thecylinder having cylinder heads, a, power shaft rotatably connected withthe cylinder, means for latching one unit of pistons to a cylinder headat the end of each step by step movement, and means for simultaneouslyreleasing the other piston unit from the cylinder head and connecting itwith the power shaft,` whereby the two units will alternately functionl0 as abutments and as power pistons.

JAMES E. GRIFFITH.

